Programmable microwave back-up warning system and method

ABSTRACT

An object detection system adapted for use on a motor vehicle during backup operations is remotely programmable. Sensor parameters can be redefined at time of installation and can be made dependent on velocity. Alarm characteristics can also be determined through programming. The same unit can thus be adapted to operate with a wide variety of different vehicle platforms, and can be customized to individual drivers or types of drivers. The sensor includes a digital-to-analog converter used to tune the microwave oscillator. Such tuning control allows for automatic calibration at the time of final test and manufacturing.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 60/218,817, filed Jul. 18, 2000, the entire content of which is hereby incorporated by reference in this application.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] NOT APPLICABLE

FIELD OF THE INVENTION

[0003] The invention relates to vehicular warning systems, and more particularly, to devices mountable on a motor vehicle for warning the vehicle operator of obstructions and/or other collisions. Still more particularly, this invention relates to an improved programmable microwave back-up warning system and method adaptable to many vehicle platforms.

BACKGROUND AND SUMMARY OF THE INVENTION

[0004] Vehicle back-up obstacle detection/collision warning systems are useful in preventing accidents and injuries. The need for an effective back-up system is evident when one considers the amount of damage low-speed backing collisions cause each year. Such collisions translate into major repair bills, countless injuries and even worse, fatalities.

[0005] A system called GUARDIAN that has been marketed and manufactured by Sense Technologies, Inc. is capable of warning a driver of the presence of any object within a defined area behind the vehicle when the vehicle is engaged in reverse gear. This GUARDIAN system employs a microwave radar technology, and applies the Doppler shift principle to detect the presence of a moving target within a certain defined range to the rear of the vehicle. This system includes dual alarms that alert drivers audibly and visually with three light-emitting diode style illuminating lights. The system provides three standard detection zones at 3 feet, 6 feet and 12 feet that are factory-adjustable, and covers the entire width of the vehicle. The system works in all weather and light conditions, senses through dirt, ice, snow, fog and other weather conditions, requires low or no maintenance, is active only when the vehicle is placed in reverse (thus eliminating annoying false alarms), and installs in less than 20 minutes with no special tools required. Such systems provide advantages such as non-contact sensing, environmental insensitivity, low cost, and the ability to “see through” composites such as fiberglass vehicle bodies. See, for example, U.S. Pat. No. RE34,773; U.S. Pat. No. 4,797,673; U.S. Pat. No. 4,864,298; and U.S. Pat. No. 5,028,920.

[0006] The GUARDIAN system has proven to be effective in dramatically increasing vehicle safety. However, further improvements are possible.

[0007] An area of desired improvement relates to the adaptability of a backup warning system to a number of different vehicle styles. All sorts of different vehicles (for example, passenger cars, light trucks, sports utility vehicles, heavy trucks, and any other type of vehicle) can benefit from a back-up warning system. However, different vehicle platforms present different constraints and requirements with respect to, for example, vehicle detection pattern size and shape. A back-up warning system for a small vehicle, for example, may need to provide a smaller detection zone than a backup warning system for a larger vehicle such as a truck or van. From a manufacturing standpoint, however, it is desirable to manufacture only a single unit that can be used with virtually any vehicle. While the prior backup warning system marketed by Sense Technologies allowed a certain degree of adjustability on the manufacturer's production floor, this technique required extra steps on the part of the manufacturer and required an installer to stock several different versions of the same product for different sized vehicles. Changing the GUARDIAN software required editing the source code and recompiling—a labor-intensive effort that could not easily be carried out on demand for a number of different end users.

[0008] I have now discovered a way to overcome this problem by providing field-programmability of a microwave backup warning system. In more detail, I provide each unit with a digital communications port that can be connected to a field programmer such as a personal computer or other device capable of downloading digital information. This field programmer can be used to program a variety of different sensor parameters at time of installation including, for example:

[0009] up to eight different programmable ranges,

[0010] priority,

[0011] velocity weighting,

[0012] turn-off time,

[0013] direction of motion prioritization,

[0014] alarm color, and

[0015] beep rate.

[0016] The example programmable microwave backup system includes a serial port adapter that can be connected to a field programming device. An external interrupt request is used to initiate programming. A special messaging data format conveys the information from the programmer to the backup unit. Software within the backup warning system restricts programmed data parameters to proper limits and verifies data downloads for accuracy and completeness.

[0017] Such programmability allows detection zones to be customized based on particular vehicle configurations. Microwave beam patterns should cover the width of the vehicle and should work right up to just behind the vehicle. Such patterns are also preferably range-gated. The detection ranges are another basic parameter which changes with vehicle platform. Programmability between zero and 10 meters plus or minus 15 centimeters is desirable. Most installers may prefer to set the particular detection range configurations to err on the side of safety. Different ranges with different degrees of urgency (e.g., yellow or red visible warning, the presence or absence of an audible alarm, and the sound the audible alarm makes) can be set and customized to provide increased safety.

[0018] I have also found programmable priority to be useful in increasing the safety and effectiveness of a microwave backup alert system. Priority relates to how fast the system makes a decision, and how soon it overrides a previous decision. Higher priorities give a greater chance of false alarms, but they also give an earlier warning of dangerous conditions. I have found that programmable priorities allow different installers to make these tradeoffs based on their own criteria—increasing system flexibility and better meeting the needs of particular customers.

[0019] In addition, I have found it useful to provide programmable parameters relating to velocity information. NHTSA studies reveal that audible alarms are typically more effective than visual ones, and that audible alarms should be loud enough to pierce ambient noise. These studies also reveal that alarm reaction time of a driver improves with experience and that false alarm rates are very important. An undue number of false alarms will cause a driver to become annoyed or begin ignoring the alarm, while system designers must nevertheless err on the side of safety so that an alarm is always issued when a true threat is presented. The probability of avoidance depends on reaction times, accelerating from rest and constant velocity. A slowly moving vehicle gives the driver more time to react to an alarm and take corrective action. A programmable microwave backup system that responds to vehicle velocity can adjust the urgency of the warnings it provides depending upon how fast the vehicle is backing up (velocity weighting). For example, I have found it to be useful to extend sensing ranges at increased velocities so the backup system can “look behind” further when the vehicle moving more rapidly. On the other hand, this “time to collision” indication may potentially confuse the driver when accelerating from rest, so I have found empirically that it is best to use velocity weighting only on the longest ranges. I have found that field programmability of this feature allows installers to reach the best tradeoff and ensure maximum safety while maximizing user convenience and user-friendliness.

[0020] Another programmable feature I have provided relates to warning turn-off time. The persistence of a particular warning can be used to approximate presence and gives the driver a sense of the urgency of the warning. A turn-off time parameter can be combined with a lack of data decision and can be made variable with range. Similarly, an audible alarm rate (i.e., the frequency of an intermittently beeping tone as one example) can also be used to give the driver a sense of urgency. A beeping recurrence that is variable from slow (e.g., intermittently switching between on and off at a slow rate) to solid (continuously on) is very helpful in attracting the driver's attention. While the system relies primarily on hearing (the driver is supposed to be looking out the back window while backing up and therefore should not be looking at a backup visual display unless the display is positioned immediately above or near the rear window), visual alarms can also be useful in attracting the driver's attention and warning him or her of potentially dangerous obstacles and/or assuring the driver that the system is operating. The system I have developed provides various visual cues such as, for example, a non-intermittent red light (most urgent), a red flashing light which flashes at a variable rate of urgency, a yellow flashing light for lower urgency situations, and a green light indicating the absence of any threat. These visual indications increase the likelihood that the driver will be informed of and pay attention to a warning.

[0021] The system I have developed also includes a direction of motion indication. An obstacle that the vehicle is closing on (or that is closing on the vehicle) presents a danger of collision, whereas an obstacle moving away from the vehicle typically does not. It may be useful to present such information to the vehicle driver. However, since such information may be confusing to some drivers, the system I have developed allows this direction-of-motion indication to be turned on and off through field programming. The indication can also be made to be range-sensitive so that the alarm persists for a variable amount of time based on range. Such a programmable range parameter increases the usefulness of the indication and minimizes the chance that it will become simply a distraction.

[0022] To further increase reliability and accuracy, our system also provides an auto calibration feature. Auto calibration can be performed by the manufacturer to increase production rate and improve accuracy. In one embodiment, the auto calibration cannot be adjusted by the end-user so as to minimize the risk that end-user will cause the system to operate in an unsafe manner.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] These and other features and advantages provided by the invention will be better and more completely understood by referring to the following detailed description of presently preferred example embodiments in connection with the drawings, of which:

[0024]FIG. 1 shows an example programmable microwave backup warning system;

[0025]FIG. 2 shows the FIG. 1 system being programmed in the field;

[0026]FIG. 3 shows an example screen display provided by the FIG. 2 field programmer;

[0027]FIG. 4 shows an example block diagram of the FIG. 1 system;

[0028] FIGS. 4A-4B show an example schematic diagram;

[0029]FIG. 5 is a flowchart of an example download routine;

[0030]FIG. 6 is a flowchart of an example initialization routine;

[0031]FIG. 7 is a flowchart of an example pulse interrupt routine;

[0032]FIGS. 8 and 8A are flowcharts of an example self-test routine;

[0033] FIGS. 9A-9C show example test results based on an example acceleration weighting parameter; and

[0034] FIGS. 10A-10C show example test results based on an example velocity weighting parameter.

DETAILED DESCRIPTION OF PRESENTLY PREFERRED EXAMPLE EMBODIMENTS

[0035]FIG. 1 shows an example programmable microwave backup warning system 20 provided in accordance with this invention. System 20 includes a rear-mounted sensing unit 22 that is mounted on or near a bumper, license plate or other portion of the rear 24 of a vehicle 26. Vehicle 26 may be, for example, a passenger vehicle, a light truck, a sports utility vehicle, a school bus, a van, or any other vehicle capable of moving in any direction relative to a surface.

[0036] Unit 22 preferably automatically detects when vehicle 26 is backing up. For example, unit 22 may be wired or otherwise coupled to the backup reverse lights 28 of vehicle 26 so that the unit receives power and/or enablement whenever vehicle 26 is put into reverse gear. In the example embodiment, unit 22 emits microwaves 34 toward the rear of vehicle 26 in a predetermined pattern 30. Microwaves 34 transmitted by unit 22 can strike obstacle 32 disposed rearwardly of vehicle 26. Such obstacles 32 reflect some of the transmitted microwaves to produce a reflected signal 34′ that is directed back toward unit 22. Unit 22 detects the reflected signals 34′ and processes them to distinguish between real obstacles and noise.

[0037] Unit 22 performs a variety of range-gated tests that may be weighted by velocity, acceleration, or other factors to distinguish between actual obstacles and false alarms. When unit 22 detects an obstacle 32 rearwardly of vehicle 26, it generates an audible and/or visual warning to warn the driver of vehicle 26 that he or she is about to strike an obstacle and should apply the brakes to stop or slow the vehicle.

[0038] Briefly, system 20 includes a transceiver adapted for mounting at the rearward end of vehicle 26. Unit 22 directs its wave output rearwardly of vehicle 26. Unit 22 is adapted for electrical connection to the backup light circuit 28 of the vehicle 26 for activation only when the vehicle transmission is engaged in reverse gear. Unit 22 produces a microwave transmission that is frequency modulated. Return wave signals 34′ for any objects 32 within the transceiver range are picked up and supplied to the transceiver by an antenna. The resultant Doppler shift signals at each frequency are sampled, amplified and applied to an internal microprocessor within unit 22 which then compares the phase difference to determine whether there is an object which is in an area that represents a threat to the vehicle 26. If a threat exists, unit 22 sounds an audible alarm adapted for placement within the passenger compartment of vehicle 26.

[0039] Unit 22 in the preferred example is remotely programmable. The sensing zones and other areas of concern can be redefined at the time of installation as well as whether they are dependent on velocity. Alarm characteristics can also be determined at this time. Thus, one unit 22 can be programmed for many different vehicle platforms. Unit 22 also includes a digital-to-analog conversion circuit to tune he microwave oscillator. This allows automatic calibration at the time of final test in manufacturing.

[0040] In more detail, because different vehicle platforms (and sometimes different drivers) have different sensing requirements, example unit 22 can be programmed in the field to set various parameters used to detect the presence of obstacles 32 behind the vehicle 26. In the FIG. 2 example, a cable 36 can be used to connect unit 22 to a field programmer 38. Field programmer 38 in one embodiment may comprise a conventional laptop or other personal computer, personal data assistant, or other digital data source. Programmer 38 develops data for use in programming sensing unit 22. Preferably, a user interacts with programmer 38 via an input device 40 and a display 42 to develop programming data. Once programmer 38 has developed appropriate programming data, the programmer downloads the data into the sensing unit 22 via cable 36. Unit 22 stores the downloaded data in non-volatile memory, and uses the data to affect and/or control the backup sensing operation shown in FIG. 1.

[0041] Example Programming Interface

[0042]FIG. 3 shows an example programming user interface display which programmer 38 may display on its display 42. The FIG. 3 example shows that programmer 38 can be used to program a number of different sensing parameters. For example, programmer 38 can be used to program up to eight different independent ranges (Range 1, Range 2, . . . Range 8). Each range has a variety of different parameters such as, for example:

[0043] range distance (0-35, for example),

[0044] priority (1-10, for example),

[0045] velocity (miles per hour, for example),

[0046] turn off time (e.g., seconds),

[0047] turn off distance (e.g., inches),

[0048] alarm indicator color (red or yellow),

[0049] alarm duration (e.g., 0-9 seconds).

[0050]FIG. 3 shows an number of additional parameters that programmer 38 may program, including, for example:

[0051] sensor self-test (on, off),

[0052] number of ranges (1-8),

[0053] direction of motion detection (on, off).

[0054] The example, using seven of the eight possible fields, shown in FIG. 3 can be filled in as desired by an operator operating programmer 38. Values developed for these fields are then formatted, compressed, and downloaded via cable 36 into unit 22. Unit 22 validates the download and the data contents, stores the parameters in an internal non-volatile memory, and uses the parameters in its operation.

[0055] Example Block Diagram

[0056]FIG. 4 shows an example block diagram of sensing unit 22. In this example, unit 22 includes a microwave oscillator 112, a digital processor 102, and a signal processor 124. Microwave oscillator 112 is coupled to a suitable microwave antenna 114 such as, for example, a strip line or other microwave antenna. Microwave oscillator 112 develops and generates microwave signals that it applies to antenna 114. Antenna 114 radiates these microwaves 34 rearwardly of the vehicle 26. Microwaves 34 may strike an obstacle 32 and be reflected to provide a reflected wave 34′ which antenna 114 receives and provides to signal processor 124 for processing.

[0057] Signal processor 124 detects and processes return signals 34′ and provides two independently sampled, amplified and thresholded outputs to digital processor 102. Digital processor 102 decides, from those outputs, whether the return signals 34′ were reflected by an obstacle or not, and responsively generates an audible and/or visual alarm on an alarm device 192 to alert the driver of vehicle 26.

[0058] Programmer 38 can be coupled to digital processor 102 via cable 36 and a conventional serial adapter 106—which may be part of programmer 38. Adapter 106 allows programmer 38 to download information into digital processor 102.

[0059] In more detail, FIG. 4 shows microwave oscillator 112 in the example embodiment as including a dielectric resonator oscillator (DRO) coupled to a tuning diode 154. Tuning diode 154 is controlled by a D/A (digital to analog) converter 194 that is part of digital processor 102. Microprocessor 190 within digital processor 102 commands D/A converter 194 to provide a programmable analog output signal that is used to control tuning diode 154 and thus the frequency at which DRO 152 operates. The microwave output of DRO 152 is coupled to antenna 114, which radiates this output. An additional control line 195 outputted by microprocessor 190 is used to control the power output generated by DRO 152. For example, control line 195 is used to turn the oscillator on and off at a predetermined rate to limit the power requirements of the sensor. This has the added advantage that it does not activate radar detectors.

[0060] The output of DRO 152 is also provided to a mixer diode 156 within signal processor 124. Reflected signals 34′ received by antenna 114 are also provided to mixer diode 156. Mixer diode 156 mixes (heterodynes) the DRO 152 output with the received signals 34′ to provide a frequency difference signal. The output of mixer diode 156 is not a microwave signal, but rather, is within a much lower frequency range representing the phase/frequency difference between the microwave signals 34 radiated by antenna 114 and the microwave signals 34′ reflected back by obstacles rearward of the vehicle. This example embodiment works based on the Doppler shift principle wherein relative movement between unit 22 and an obstacle 32 produces a Doppler shift. It is this Doppler shift that is detected and isolated by mixer diode 156 in the example embodiment.

[0061] The output of mixer diode 156 is provided to two different signal processing channels 162, 164. Each of these channels 162, 164 comprises sample and hold circuitry (170, 172), amplifier stages (176, 178), and comparators (182, 184). In one embodiment, signal processor channels 162, 164 may be identical to one another. Microprocessor 190 can independently control the sample and hold circuitry 170, 172 to sample mixer diode 156 output at different times. Microprocessor 190 can use these different channels 162, 164 to acquire the Doppler shift outputs at different time instants.

[0062] Microprocessor 190 executes software stored within an operational program memory 193 to analyze the outputs of signal processor 124 and to generate the various control signals discussed above. An analytical program 191 operating based on data parameters stored in EEPROM memory 196 is used to apply different range gates, weight values based on velocity and/or acceleration and perform other signal processing tasks. Microprocessor 190 operating under software control may activate audible and/or visible alarm(s) 192 based upon the determination(s) whether or not an obstacle has been detected and the nature of the threat (e.g., urgent, somewhat urgent, or not at all urgent).

[0063] In the example embodiment, microprocessor 190 receives its power from a power supply 186 that is coupled to the vehicle backup light circuit 28. It is relatively convenient in at least some vehicles to simply tap power off the backup light circuit and use the presence of power to activate and enable unit 22. In other installations, it may be desired to provide optical or other coupling to the backup lights and/or associated circuitry. In still other installations, unit 22 could be powered constantly and detect that the vehicle is moving rearwardly through any desired means.

[0064] Detailed Example Circuitry

[0065]FIG. 4A is a schematic diagram of an example signal processor 124. In this particular example, the output of mixer diode 156 is applied to an emitter follower amplifier 186 for isolation, and is sampled by sample-and-hold circuits 170, 172 at instants controlled by microprocessor 190. The outputs of sample-and-hold circuits 170, 172 are amplified by cascaded operational amplifier stages (176 a, 176 b; 178 a, 178 b), before being thresholded by comparators 182, 184. The output of comparators 182, 184 are applied independently to input ports of microprocessor 190 (see FIG. 4B).

[0066] The FIG. 4B example schematic diagram of digital processor 102 includes a D/A converter 194 implemented with a resistor network 194 a coupled to an operational amplifier 194 b to provide a variable tuning voltage for application to tuning diode 154 and DRO 152. Microprocessor 190 in this embodiment can turn DRO 152 on and off at will via a switching transistor 153 and also control its frequency through D/A converter 194. Microprocessor 190 can also generate “far range” and “near range” control output signals via field effect transistors 156 a, 156 b to control external alarms (connections not shown).

[0067] An interrupt request input IRQ of microprocessor 190 is coupled to one pin of a serial programming port 106. Two other pins of the programming port 106 are coupled to an input and an output, respectively, of microprocessor 190 for use as serial transmit and serial receive. Through these transmit and receive lines and the interrupt request line, an external device such as programmer 38 coupled to port 106 can communicate bidirectionally with microprocessor 190. Microprocessor 190 may, in turn, read information from and write information to EEPROM 196. Information stored within EEPROM 196 is non-volatile, i.e., it remains there even after power to unit 22 has been turned off. A serial type EEPROM 196 is used in the FIG. 4B example, but various other types of non-volatile memory devices (e.g., parallel EEPROM, flash memory, battery backed RAM memory, etc.) could be used in other arrangements.

[0068] The following are additional example specifications of the detailed circuitry shown in FIGS. 4A and 4B:

[0069] input voltage 10-28 VDC automotive grade;

[0070] power 600 mw;

[0071] temperature range −40 C. to +85 C. Sensor, −20 C. to +70 C. display;

[0072] humidity 95%RH;

[0073] sensor-range gated microwave Doppler;

[0074] FCC-10.525 GHz approved;

[0075] MTBF-99 years;

[0076] display sound level-95 dbm@3 m;

[0077] display sound frequency-4 KHz.

[0078] Example Software Functionality

[0079] FIGS. 5-8A are flowcharts of example steps performed by software executing on sensor unit microprocessor 190 in the example embodiment. FIG. 5 is an example software download routine used to download software into unit 22; FIG. 6 is an example initialization routine used to initialize unit 22 upon reset (e.g., power on); FIG. 7 is an example pulse interrupt routine performed in response to receipt of a timing pulse; and FIGS. 8 and 8A are flowcharts of example steps performed during a self-test and calibration routine.

[0080] Referring to the FIG. 5 example download routine, microprocessor 190 responds to an interrupt request from serial connector 106 (block 202) by transmitting a “ready” message block 204 over the “xmit” serial connector pin 106. Microprocessor 190 then sets the DRO 152 tuning voltage to a default center value through selection of an appropriate one of the resistors within resistor network 194 a (block 206), and waits for an input character (block 208). Upon receiving an input character, microprocessor 190 decodes the character by testing to see whether it comprises certain character values. In this particular example, characters of significance are:

[0081] “U” (tune DRO 152 to decrease its frequency),

[0082] “D” (tune DRO 152 to increase its frequency),

[0083] “H” (send help menu),

[0084] “T” (write tuning voltage to EEPROM 196),

[0085] “C” (configure),

[0086] other characters.

[0087] In response to receipt of the “U” character (decision block 210), microprocessor 190 increases the tuning voltage of DRO 152 and sends back a message verifying that this has been done (block 212). Similarly, in response to the “D” character (decision block 214), microprocessor 190 decreases DRO 152 tuning voltage and sends back a verification (block 216). By sending a sequence of “U” and “D” characters to unit 22, programmer 38 can interactively adjust the microwave frequency of the unit. When the operator of programmer 38 is satisfied with the tuning frequency, the programmer 38 may send a “T” character (decision block 222) which controls microprocessor 190 to write the current tuning parameter to the EEPROM memory 196 for use as the default DRO 152 tuning voltage which will remain in effect until changed (block 224). Unit 22 will send a “help” menu with explanations at any time in response to receipt of a “H” character (block 218, 220).

[0088] In response to receipt of a “C” character (decision block 226), microprocessor 190 receives a parameter string from programmer 38 (block 230) and writes that parameter string to an appropriate location(s) within EEPROM memory 196 (block 232). In this example, microprocessor 190 reads the string it has written back out of the EEPROM 196 (block 234) and sends it back to programmer 38 (block 236) for verification purposes. In this way, programmer 38 can rewrite any of a variety of different parameters used to control the operation of unit 22 including, for example, a number of range gates in effect, the range of each, the priority of each, any velocity weighting to be applied, turn off time in seconds and inches, alarm color indicator and duration, etc. See FIG. 3.

[0089] The FIG. 6 flowchart of an example initialization routine 250 shows example steps performed by microprocessor 190 upon power-on reset. Referring to FIG. 4B, a power-on reset circuit 190 a is used to apply a reset signal to microprocessor 190 each time power is initially applied. In one example, power is applied to unit 22 only when the backup lights 28 of vehicle 26 are on—meaning that unit 22 resets each time the driver puts the vehicle into reverse.

[0090] In this FIG. 6 example, initialization routine 250 begins (block 252) by microprocessor 190 setting its various input/output ports appropriately for the various inputs and outputs shown in FIG. 4B (blocks 254, 256, 258). Microprocessor 190 then uses an internal timer mechanism to set a predetermined time delay (block 260) and reads EEPROM 196 for the parameter data it contains (block 262). Microprocessor 190 then enters a loop in which it clears all outputs (block 264) and reads a “norm/cw” test point state (see FIG. 4B) (block 266). If the “norm/cw” test point state is active (“yes” exit to decision block 266), microprocessor 190 determines whether the “tuning” test point indicates a “high” or “low” state (decision block 268). If the “tuning” test point is “high,” microprocessor 190 sets the DRO 152 tuning voltage high (block 270). Otherwise, microprocessor 190 sets the DRO 152 tuning voltage low (block 272). The functionality provided by blocks 266-272 in response to the states of the “norm/cw” and “tuning” test points (see FIG. 4B) are used during factory calibration for example to ensure proper operation.

[0091] Assuming the “norm/cw” test point is not active (“no” exit to decision block 266)—i.e., the normal state of unit 22 as installed on vehicle 26—microprocessor 190 will proceed to set various defaults in its output state. For example, microprocessor 190 may clear all range counters (block 274) and set the last range register to “FF” or other default value (block 276) in preparation for upcoming range detection operations. Microprocessor 190 may clear its output ports (block 278) and set various toggle values for later use (block 280). Microprocessor 190 in this example also turns a “yellow” display indicator off (block 282), sets display 192 to turn-off or green (block 284), resets an overtimer (block 286), resets a towards/away counter (block 288), and then goes to a “get edge” routine for obstacle detection (block 290).

[0092]FIG. 7 shows an example “pulse interrupt” routine that microprocessor 190 performs to send out and receive microwave pulses using DRO 152. This example pulse interrupt routine 200 performs a variety of functions including, for example, toggling the display state to cause visual indicators to flash and audible alarms to beep; pulse the DRO 152; control the sample-and-hold operations of the signal processor; and reset unit at an appropriate time to begin a new signal acquisition cycle.

[0093] The example “pulse interrupt” routine 300 begins with microprocessor 190 turning off display 192 if necessary (block 302), delaying for a certain parameter, and then turning on the DRO 152 (block 304). Microprocessor 190 reloads a timer to time the DRO 152 on time, turns on display 192, and then activates the channel B sample-and-hold circuit 172 (block 306) to acquire any return signal (block 306). Microprocessor 190 waits a further predetermined delay and then turns off the “channel B” sample-and-hold circuit 172 and turns on the channel A sample-and-hold circuit 170 (block 310). After another predetermined delay, microprocessor 190 turns off the channel A sample-and-hold 170, turns off DRO 152 (block 312), and resets the timer for subsequent use (block 314). At this point, microprocessor 190 has controlled the acquisition of two input samples that can be used for a Doppler shift detection. The actual process of detecting an obstacle and determining how much of a threat the obstacle is can be performed as in the prior GUARDIAN product except that the detection software is parameterized with a set of parameters stored in a particular location in the EEPROM.

[0094] Microprocessor 190 next checks whether a certain flag is set (decision block 316). If the flag is set (“yes” exit to decision block 316), microprocessor 190 decrements an over-timer counter (block 318) which is used to time an over-timer time delay. Microprocessor 190 tests whether the over-timer period has completed (decision block 320). If the overtime period has completed (“yes” exit to decision block 320), microprocessor 190 resets its stack pointer (block 322), and transfers control to the “clear out” block 264 of FIG. 6.

[0095] Assuming the over-timer time delay is not over (“no” exit to decision block 320), microprocessor decrements a toggle counter least-significant bit (block 324) and test whether the toggle counter is now equal to zero (decision block 326). If the bit is equal to zero (“yes” exit to decision block 326), microprocessor 190 begins to toggle the display 192 by turning the display on for a predetermined time period. Routine 300 then returns (blocks 328, 330). Otherwise, if the toggle counter is not equal to zero (“no” exit to decision block 326), microprocessor turns on the display (block 332), and decrements the toggle counter most significant bit (block 334). If the toggle is then over (“yes” exit to decision block 336), routine 300 returns (block 338). Otherwise, if the toggle is not yet over (“no” exit to decision block 336), microprocessor 190 resets the toggle counter (block 340), sets the toggle flag (block 342), and returns (block 344). Such operations are used to toggle the display 192 between on and off for less urgent (e.g., “yellow”) alerts (in the example embodiment, a more urgent “red” alert is turned on continually).

[0096] Referring now to the FIG. 8 example self-test routine, microprocessor 190 begins by setting its ports (block 402) and performing a one-second delay (block 404). Microprocessor 190 then presets its success and fail counters (block 406), initializes a timer (block 408), and begins certain self-test operations. For example, microprocessor 190 tests a flag (block 410) and if the flag is set, microprocessor reads the timer value and stores a “set edge” flag (block 412), changes the edge, and resets a flag (block 414). Then (or if the flag was not set), microprocessor 190 tests a further flag (block 416). If the further flag is not set (“no” exit to decision block 416), microprocessor continues to loop (block 410-416) until the operation is complete and the further flag becomes set (“yes” exit to decision block 416). Upon completion, microprocessor 190 calls a “period” routine shown in FIG. 8A (block 418), and then determines whether an edge flag is set (decision block 420). If the edge flag is not set (“no” exit to decision block 410), microprocessor 190 performs an elaborate routine to detect edges. In particular, microprocessor 190 determines the states of its various flags (decision blocks 422, 424), and in response, may perform a series of operations to transfer the previous edge (block 426), reset various parameters in preparation for receipt of the next edge (block 428), calculates the period between successive edges (block 430), tests whether that value is within limits (block 434), and may also test whether the outputs of comparators 182, 184 are the same (block 436).

[0097] If the “in limits” test (block 434) fails, then microprocessor 190 may clear a success counter (block 438) and increment a fail counter (block 440), and then tests whether the failure rate is over a predetermined limit (block 442). If the failure limit is over a predetermined (“yes” exit to decision block 442), microprocessor 190 can reach a determination that unit 22 has failed (block 444) and light a red display indicator to indicate this fact (block 446). Otherwise, if the “in limits” test was successful (“yes” exit to decision blocks 434, 436), microprocessor 190 increments a success counter (block 444) and then determines whether the self-test routine is complete (block 446). If not complete (“no” exit to decision block 446), microprocessor 190 can return to block 422 for further tests. If finished (“yes” exit to decision block 446), unit 22 sounds a beep (block 452) and terminates the self-test routine (block 454).

[0098]FIG. 8A is a flowchart of the “period” routine that called by block 423. In this example, the “period” routine changes the DRO 152 drive (i.e., turns the DRO on if it was previously off or off if it was previously on), sets a timer for predetermined value (e.g., 1 ms), resets a timer flag (block 423 b), then resets the edge flag and the “com” timer (block 423 c) before returning (block 423 b).

[0099] Example Test Results

[0100] FIGS. 9A-9C and 10A-10C show example test results of unit 22. FIG. 9A shows an example collision avoidance graph plotting percentage of collisions avoid versus distance to the objects in feet using acceleration weighting. FIG. 10A shows a similar plot using velocity weighting. FIG. 9B plots acceleration versus relative weighting, and FIG. 9C plots driver reaction time versus relative weighting. FIG. 10B plots velocity in miles per hour versus relative weighting, and FIG. 10C plots driver reaction time in seconds versus relative weighting.

[0101] While the invention has been described in connection with what I believe are the most practical and preferred example embodiments, other variations are possible. For example, our preferred embodiment provides a backup warning for a motor vehicle, but detection of obstacles and/or danger of collision from any direction (e.g., side or front) of any vehicle type are also contemplated. In addition, some or all of the techniques disclosed herein could be used in connection with a stationery sensing unit that monitors objects moving with respect to it. While the preferred example embodiment uses microwaves and senses based on the Doppler shift principle, other types of electromagnetic or other waves can be used, and different detection techniques (e.g., pulse-echo) could be used instead. Furthermore, although our preferred example provides a visual and audible warning, other types of warnings based upon other senses (e.g., touch) might be used. The invention is intended to cover all such variations and alternatives as limited only by the scope of the claims. 

I claim:
 1. A programmable microwave backup sensor for use with a motor vehicle, said sensor receiving and storing data from a source external to said sensor and using said received and stored data as at least one parameter for sensing object.
 2. A sensor as in claim 1 wherein said parameter comprises the number of range gates.
 3. The sensor of claim 1 wherein said parameter comprises the range of at least one range gate.
 4. The sensor of claim 1 wherein said parameter comprises a range gate priority.
 5. The sensor of claim 1 wherein said parameter comprises a velocity weighting factor.
 6. The sensor of claim 1 wherein said parameter comprises warning duration.
 7. The sensor of claim 1 wherein said parameter comprises warning distance.
 8. The sensor of claim 1 wherein said parameter comprises visual urgency indication.
 9. The sensor of claim 1 wherein said parameter comprises warning duration.
 10. The sensor of claim 1 wherein said parameter comprises a self-test operation initiator.
 11. The sensor of claim 1 wherein said parameter comprises an oscillator control command.
 12. The sensor of claim 1 wherein said parameter comprises the number of range gates to be in effect.
 13. A method of programming a microwave sensing system comprises: coupling a programming device to said microwave sensing system; downloading control parameter information from said programming device to said sensor system; storing said downloaded information within said sensor system; and operating said sensor system in accordance with said downloaded information.
 14. A backup microwave sensing device for vehicular use, said device including a microwave oscillator and a Doppler shift detection arrangement, an improvement comprising a programmable memory within said device, said programmable memory being accessible via a programming port accessible externally of said device, said device performing at least certain sensing operations in response to information stored within said programmable memory.
 15. A microwave backup sensing system for vehicular use, said system including an auto-calibration function and a self-test function, said auto-calibration and self-test functions making use of a display/warning indication that is also used for normal operation of said system in detecting objects behind a vehicle. 